Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/powerpc/boot/ops.h b/arch/powerpc/boot/ops.h
index cd04372..e060676 100644
--- a/arch/powerpc/boot/ops.h
+++ b/arch/powerpc/boot/ops.h
@@ -251,6 +251,8 @@
 extern char _initrd_end[];
 extern char _dtb_start[];
 extern char _dtb_end[];
+extern char _esm_blob_start[];
+extern char _esm_blob_end[];
 
 static inline __attribute__((const))
 int __ilog2_u32(u32 n)